Blurry usually means someone has been hand holding the camera - this is usually not an option as night shots require long exposure.
Assuming you have a digital camera:
DO NOT USE FLASH!
Put the camera on a firm base. If you don't want to lug a tripod around, find a nearby trash can or wall.
Set the camera to automatic and if it has a self timer, use that (so there is less chance of moving the camera when pressing the button to take the picture).
Your camera may tell you what settings it used when automatically taking the picture. Look at the end result and if you think it looks over exposed then manually take over and set the exposure time for less. Reverse is true if it looks too dark.
If you have a film camera, much of the above is still true, bar your not being able to look at the results then and there.